The present invention relates to a document feeder for an imaging device such as a scanner, facsimile, or the like, and in particular, to an apparatus for the improved feeding of documents, especially short documents, to high speed image scanning equipment. Specifically, the present invention relates to a feed roller apparatus having a picking (PIC) roller and an infeed roller which are selectively, independently driven responsive to a sensor.
It is well known in the art of imaging/printing equipment to use a document feeder to support a stack of documents, and feed these documents to the imaging/printing equipment, one at a time from the stack. With respect to imaging equipment, a picking (PIC) roller of a skimmer apparatus typically propels the first sheet to an infeed roller, which then feeds the sheet to the imaging equipment.
However, special problems arise when it is attempted to feed sheets of a limited length, i.e., short sheets, to the imaging equipment. Known feeders have not been able to adequately feed such short sheets to the imaging equipment.
In prior art devices, the PIC roller and the infeed roller are driven together. In the case of short sheets, the first sheet typically clears the PIC roller too soon (i.e., before enough of the first sheet is fed by the infeed roller); thus exposing the PIC roller to the second sheet too soon. As a result, since the PIC roller is still rotating, the second sheet will be driven forward too soon, resulting in buckling of the second sheet. This can lead to paper jams, improper feeding, and/or the damage to the sheets such as by folding or creasing, etc.
While there are numerous prior art apparatus for feeding documents, there are no known apparatus that can adequately feed short sheets to imaging equipment. Such prior art devices cannot achieve the advantages and improvements achieved by the present invention.
Accordingly, there is a need for an apparatus for feeding short documents to select equipment, one at a time, in a smooth, efficient and continuous manner, without misfeeding or damaging the documents or creating paper jams. The present invention fulfills such a need.
The present invention relates to a feeder roller apparatus for high speed image scanning equipment, which improves feeding of documents, and in particular, short documents. Documents or sheets are sequentially fed from a stack via a PIC roller and an infeed roller. The invention comprises a feeder roller apparatus which selectively, independently drives the PIC roller and the infeed roller.
The PIC roller and the infeed roller of the present invention are driven via a dual drive shaft, composed of an inner drive shaft and an outer drive shaft, which are driven either together or selectively, independently by a main motor. An electro-mechanical clutch, when energized is used to drive the PIC roller. A sensor is provided downstream of the rollers to recognize when a document is being fed. Initially, the clutch is energized, and both rollers are driven. When the first sheet reaches the sensor, the clutch is de-energized, cutting off the drive to the PIC roller. The main motor continues driving only the infeed roller until the first sheet is fed out of the feeder and into the transport of the scanning equipment.
Accordingly, it is the principal object of the present invention to provide an apparatus for feeding documents to imaging/printing equipment.
It is also an object of the invention to provide a feeder apparatus for feeding short documents to high speed image scanning equipment.
It is an additional object of the present invention to provide a feeder having a PIC roller and an infeed roller which are selectively, independently driven.
It is another object of the present invention to provide a dual shaft drive system having a clutch for selectively disengaging a PIC roller in response to a sensor sensing a document being fed by an infeed roller.
It is a further object of the present invention to provide a method and apparatus for feeding a stack of documents, and especially short documents, one at a time from the stack to any desired equipment in a controlled, precise manner to avoid paper jams, misfeeding or damage to the documents.
Numerous other advantages and features of the invention will become readily apparent from the detailed description of the preferred embodiment of the invention, from the claims, and from the accompanying drawings in which like numerals are employed to designate like parts throughout the same.